Preparative-scale chromatography fraction collection

Cyclone separators can be effective as collection devices in SFC. However, they tend to be best suited for semipermanent applications, like preparative-scale chromatography. They are not user friendly for the separation of a large number of different samples in a short time. Each fraction requires a separate cyclone separator. For modest scale separations, the cyclone separators are bulky, with a very large internal surface area, which is difficult to clean out. Because they are subjected to relatively high pressures, they are usually made of stainless steel. Connections are usually made with large-diameter stainless-steel tubing and the whole apparatus is bolted to some sort of rack mount. One could think of this approaches a scaled-down pilot plant. 

Experimental campaign bulk or in-process control samples (e.g., prior to recrystallization) are excellent sources of process-related impurities and are a vital component of the KPSS. Isolated fractions collected from a preparative or semi-preparative liquid chromatography (LC) system are also excellent KPSS samples. Sometimes small-scale synthesis of the impurity or degradant is possible and less time-consuming than the isolation techniques. 

LC Separation. Preparative scale liquid chromatography was performed with Waters PrepPak radially compressed silica columns. Fuel charges of 6 to 10 ml were carried through the column with n-pentane at a flow of 200 ml/minute. Refractive index, 254 nm ultraviolet, and 313 nm ultraviolet detectors monitored the LC effluent and keyed the collection of fractions. 

In these, the gas phase is suitably collected and subjected to the subsequent analytical determinations in a discontinuous fashion. Although the classical distillation systems have fallen into disuse since the advent of the advantageous gas chromatography, their automation has fostered the development of assemblies of some Interest. Chipperfleld et al. [2] reported a computer-controlled laboratory fractional column for small-scale preparations in which a microcomputer controls the column-jacket temperatures, boil-up rate and reflux ratio to achieve optimum separations. A schematic diagram of the dls-... 

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